The removable of the remanence of knocked-off sprues and risers from raw-cast workpieces is normally accomplished by techniques such as grinding, cutting or sawing and the removal of flashings is then accomplished either manually by means of grinding discs or sanding belts or else by such devices as jet blasting machines. Operations using these various techniques require different machine installations, frequent clamping and handling of the workpieces, additional transportation paths and considerable manpower and is thus unprofitable.
It has been known to use combinations of machines for the removal of flashing wherein outside flashings are removed by grinding and inside flashings are removed by thrust tools which are adapted to the corresponding shape of the casting. One such system is known as the Sutter system and is shown in a prospectus number GA125/1 Georg Fischer AG. Such machines are economically advantageous only in the situation where there is a large number of workpieces of substantially the same shape and can be used only for very few workpieces which differ from each other in shape. Sprues and risers, in such an operation, must be removed beforehand on separate machines or by hand.
Milling machines of general construction are known by which the remanents of sprues or risers, and to some degree also flashings, may be milled off. The removal of inside and outside flashings, especially in the case of contours with inside corners, is not possible in the case of workpieces of varying shapes with such milling machines in one clamping operation. It is, as a minimum, necessary to reposition the workpiece between steps of the operation.